Optical semiconductor element mounting package, and optical semiconductor device using the same

ABSTRACT

An optical semiconductor element mounting package that has good adhesion between the resin molding and the lead electrodes and has excellent reliability is provided, as well as an optical semiconductor device using the package is also provided. The optical semiconductor element mounting package having a recessed part that serves as an optical semiconductor element mounting region, wherein the package is formed by integrating: a resin molding composed of a thermosetting light-reflecting resin composition, which forms at least the side faces of the recessed part; and at least a pair of positive and negative lead electrodes disposed opposite each other so as to form part of the bottom face of the recessed part, and there is no gap at a joint face between the resin molding and the lead electrodes.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation application of U.S. application Ser.No. 12/303,188, filed Dec. 2, 2008, which is a 371 of internationalapplication PCTJP2007/060385 filed May 21, 2007. This application isalso a continuation application of U.S. application Ser. No. 13/160,680,filed Jun. 15, 2011, which is a divisional application of U.S.application Ser. No. 12/303,188, filed Dec. 2, 2008, which is a 371 ofinternational application PCTJP2007/060385 filed May 21, 2007, theentire contents of each of which are incorporated herein by reference.

TECHNICAL FIELD

This invention relates to an optical semiconductor element mountingpackage that is useful in manufacturing an optical semiconductor devicethat combines an optical semiconductor element with a wavelengthconversion means such as fluorescent material, and to an opticalsemiconductor device using the package.

BACKGROUND

Optical semiconductor devices (light emitting devices) of the SMD(surface mounted device) type and having the structure shown in FIG. 3have often been used in recent years in place of a lead type of opticalsemiconductor device in an effort to reduce the size and thickness ofthe optical semiconductor device. With a surface mounted type of opticalsemiconductor device, usually an optical semiconductor element (LED,etc.) 400 is mounted via a die-bonding material 406 on the bottom faceof a recessed part of an optical semiconductor element mounting packagein which positive and negative lead electrodes 404 are integrated with aresin molding 403 having a recessed part that serves as the region wherethe optical semiconductor element will be mounted. And then, the opticalsemiconductor element 400 and the lead electrodes 404 are electricallyconnected with a bonding wire 401, after which the recessed part ispacked with a transparent sealing resin 402 that includes a fluorescentmaterial 405, and the optical semiconductor element 400 is sealed tocomplete the manufacture of the optical semiconductor device. Theabove-mentioned optical semiconductor element mounting package isusually manufactured by placing lead electrodes in a mold, injecting amolten thermosetting resin composition into the closed mold, andreturning the resin composition to room temperature to cure it andintegrate the components. Japanese Laid-Open Patent Applications2002-280616, 2004-055632, and 2004-342782 disclose an SMD-type LEDapparatus that makes use of an optical semiconductor element mountingpackage in which positive and negative lead electrodes and a resinmolding having a recessed part are integrated.

DISCLOSURE OF THE INVENTION

Optical semiconductor devices have come to be used in a wide range offields, and it has become increasingly common in recent years for themto be used under harsh conditions, which means that these devices needto have higher reliability than what was needed in the past. However,the thermosetting resin compositions that are commonly used to producethe above-mentioned resin moldings have a coefficient of linearexpansion (20 to 120 ppm/° C.) that is greater than the coefficient oflinear expansion (approximately 17 ppm/° C.) of the copper that istypically used for lead electrodes, so a great deal of stress isgenerated when these materials are integrated, and this results in adecrease in adhesion between the resin molding and the lead electrodes,producing a gap on the order of a few dozen microns in between. If theadhesion between the resin molding and the lead electrodes decreases,the stress applied in the course of bending the outer leads of the leadelectrodes will also create such a gap, and this lowers the reliabilityof the optical semiconductor device.

Also, if injection molding is employed in the production of a resinmolding by injecting a resin composition into a mold, the injectionpressure of the resin may produce a slight deformation of the mold, inwhich case resin flash (a parting line) is produced on the side faces ofthe optical semiconductor element mounting package. This resin flashbecomes a hindrance in the forming process, and makes it extremelydifficult to accurately work outer leads to match the outer faces of theresin molding in order to reduce the size of the optical semiconductordevice. Also, stress is applied in the longitudinal direction at theboundary between the resin molding and the lead electrodes here, and agap is produced at this boundary from the distal end portion of theflash extending in the lateral direction. Furthermore, there is the riskthat the resin flash will separate, and if this happens, it can causecracking in the package, moisture or foreign matter may get in throughthese cracks, and this greatly diminishes the reliability of the opticalsemiconductor device. Also, if the flash separation is deep, it cancreate a void that mars the appearance of the device.

Also, optical semiconductor elements having an emission peak wavelengthin the ultraviolet band, for example, have been developed in recentyears, and these elements hold much promise in their application toSMD-type LEDs, but because light near the ultraviolet band has such highenergy, it tends to degrade the recessed part inner peripheral face(reflector) of the resin molding, and as this degradation of the innerperipheral face progresses, even reflectivity of visible light willdecrease.

DISCLOSURE OF THE INVENTION

In view of this situation, it is an object of the present invention toprovide an optical semiconductor element mounting package that has goodadhesion between the resin molding and the lead electrodes and hasexcellent reliability, as well as an optical semiconductor device usingthe package.

It is another object of the present invention to provide an opticalsemiconductor element mounting package that has a recessed part(reflector) with high reflectivity of light ranging from visible lightto near-ultraviolet light after curing, and excellent light resistanceand thermal degradation resistance, as well as an optical semiconductordevice using the package.

Specifically, the present invention is characterized by the followingitems (1) to (12).

(1) An optical semiconductor element mounting package having a recessedpart that serves as an optical semiconductor element mounting region,wherein the package is formed by integrating: a resin molding composedof a thermosetting light-reflecting resin composition, which forms atleast the side faces of the recessed part; and at least a pair ofpositive and negative lead electrodes disposed opposite each other so asto form part of the bottom face of the recessed part, and there is nogap at a joint face between the resin molding and the lead electrodes.

(2) The optical semiconductor element mounting package according to (1)above, wherein the integration of the resin molding and the positive andnegative lead electrodes is performed by transfer molding.

(3) The optical semiconductor element mounting package according to (1)or (2) above, wherein the thermosetting light-reflecting resincomposition includes a filler.

(4) The optical semiconductor element mounting package according to (1)or (2) above, wherein the thermosetting light-reflecting resincomposition includes components: (A) an epoxy resin; (B) a curing agent;(C) a curing accelerator; (D) an inorganic filler; (E) a white pigment;and (F) a coupling agent, and is a resin composition whose opticalreflectivity at a wavelength of 350 to 800 nm is at least 80% and whichcan be press molded at normal temperature (0 to 35° C.).

(5) The optical semiconductor element mounting package according to (4)above, wherein the inorganic filler (D) is at least one type selectedfrom the group consisting of silica, alumina, magnesium oxide, antimonyoxide, aluminum hydroxide, magnesium hydroxide, barium sulfate,magnesium carbonate, and barium carbonate.

(6) The optical semiconductor element mounting package according to (4)or (5) above, wherein the white pigment (E) is inorganic hollowparticles.

(7) The optical semiconductor element mounting package according to anyof (4) to (6) above, wherein the average particle size of the whitepigment (E) is between 0.1 and 50 μm.

(8) The optical semiconductor element mounting package according to anyof (4) to (7) above, wherein the total amount of the inorganic filler(D) and the white pigment (E) is from 70 to 85 vol % with respect to theentire thermosetting light-reflecting resin composition.

(9) The optical semiconductor element mounting package according to anyof (1) to (8) above, wherein the spiral flow of the thermosettinglight-reflecting resin composition is at least 50 cm and no more than300 cm.

(10) The optical semiconductor element mounting package according to anyof (1) to (9) above, wherein the disk flow of the thermosettinglight-reflecting resin composition is at least 50 mm.

(11) The optical semiconductor element mounting package according to anyof (1) to (10) above, wherein the coefficient of linear expansion of thethermosetting light-reflecting resin composition is 10 to 30 ppm/° C.

(12) An optical semiconductor device, comprising: the opticalsemiconductor element mounting package according to any of (1) to (11)above; an optical semiconductor element mounted on the bottom face of arecessed part of the package; and a transparent sealing resin layer thatcovers the optical semiconductor element in the recessed part.

With the present invention, it is possible to provide an opticalsemiconductor element mounting package that has good adhesion betweenthe resin molding and the lead electrodes and has excellent reliability,as well as an optical semiconductor device using the package, andfurthermore it is possible to provide an optical semiconductor elementmounting package that has a recessed part with high reflectivity oflight ranging from visible light to near-ultraviolet light after curing,and excellent light resistance and thermal degradation resistance, aswell as an optical semiconductor device using the package.

In the present invention, saying that “there is no gap” at the jointface between the resin molding and the lead electrodes refers to a statein which no gap is observed at the interface where the resin moldingcomes into contact with the lead electrodes when this interface isobserved at a magnification of 200 times using a SEM, metal microscope,or the like.

Also, this application includes a claim of priority right based onJapanese Patent Application 2006-154652 (application date: Jun. 2, 2006)already filed by the applicant of the present invention, and theSpecification thereof is included herein for the sake of reference.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an oblique view and a cross section of an embodiment of theoptical semiconductor element mounting package of the present invention.

FIG. 2 is a cross section of an embodiment of the optical semiconductordevice of the present invention.

FIG. 3 is a cross section of a typical SMD-type LED (opticalsemiconductor device).

FIG. 4 is a cross section of a favorable structure of the lead electrodeends of the optical semiconductor element mounting package of thepresent invention.

BEST MODE FOR CARRYING OUT THE INVENTION

The optical semiconductor element mounting package of the presentinvention is an optical semiconductor element mounting package having arecessed part that serves as an optical semiconductor element mountingregion, wherein the package is formed by integrating: a resin moldingcomposed of a thermosetting light-reflecting resin composition, whichforms at least the side faces of the recessed part; and at least a pairof positive and negative lead electrodes disposed opposite each other soas to form part of the bottom face of the recessed part, and there is nogap at the joint face between the resin molding and the lead electrodes.Preferably, one end of the positive lead electrode and one end of thenegative lead electrode are disposed opposite each other so as to formthe bottom face of the recessed part, with the surface (main face) ofeach exposed, and the ends are separated by molding resin in betweenthem. It is also preferable if the other end of the positive leadelectrode and the other end of the negative lead electrode are providedso as to protrude from the resin molding side faces immediately afterintegration with the resin molding, and the protruding outer lead partsthereof are, as shown in FIG. 3, for example, bent toward the inside ofthe joint face of the package molding, producing J-bend positive andnegative connection terminals. Naturally, the structure of theconnection terminals in the present invention is not limited to a J-bendtype, and may be a gullwing type or another such structure.

The constitution and manufacturing method of the optical semiconductorelement mounting package of the present invention, as well as an opticalsemiconductor device using the package, will now be described in detail.

<Lead Electrodes>

The lead electrodes can be constituted by steel-containing copper oranother such material with high thermal conductivity. For example, ifcan be formed by using a press so as to punch out a metal strip composedof a copper alloy with a thickness of 0.15 mm. The surface of the leadelectrodes may be plated with metal such as silver, aluminum, gold,palladium, and an alloy of these, etc., in order to prevent oxidation ofthe lead electrodes and so forth. Also, the surface of the leadelectrodes is preferably made smooth in order to increase opticalreflectivity from a light emitting element. Also, the surface area ofthe lead electrodes is preferably made as large as possible, whichenhances heat dissipation, effectively suppresses an increase in thetemperature of the light emitting element that is installed, and alsoallows more power to be sent to the light emitting element, so opticaloutput can be increased.

Also, with the present invention, at least a pair of positive andnegative lead electrodes are disposed opposite each other so as to formpart of the bottom face of the recessed part of the package, butpreferably the corners at which the rear face and side faces intersectis curved at the ends of the opposing lead electrodes (see R1 in FIG. 4;furthermore, the “rear face of the lead electrode” is the back of theface (main face) exposed at the bottom of the recessed part of thepackage). If the lead electrode ends are thus rounded off in thedirection in which the molding resin is injected, the molding resin willmore readily fill in between the lead electrodes without leaving anygaps, the lead electrodes can be separated from one another moreeffectively, and adhesion is increased between the lead electrodes andthe resin molding. Furthermore, since the joint line between the resinmolding and the lead electrodes is curved, less stress will beconcentrated at the joint line, and this reduces the occurrence ofpackage cracking.

Meanwhile, the corners at which the side faces and the main faceintersect at the ends of the opposing lead electrodes are preferablybuilt up to an acute angle (see R2 in FIG. 4). This effectively preventsthe molding resin from flowing out from between the lead electrodes ontothe main face of the lead electrodes, and prevents defective die bondingor wire bonding of the light emitting element. It also increasesadhesion between the lead electrodes and the molding resin, and reducesseparation at the interface between them.

<Resin Molding>

The resin molding in the package of the present invention is preferablymolded from a thermosetting light-reflecting resin composition. Thethermosetting light-reflecting resin composition preferably contains afiller. Further, the thermosetting light-reflecting resin compositionpreferably contains components: (A) an epoxy resin; (B) a curing agent;(C) a curing accelerator; (D) an inorganic filler; (E) a white pigment;and (F) a coupling agent.

The above-mentioned epoxy resin (A) can be any commonly used epoxy resinmolding material for sealing electronic components, examples of whichinclude epoxified novolac resins of phenols and aldehydes, such asphenol novolac type epoxy resin or orthocresol novolac type epoxy resin;diglycidyl diethers of bisphenol A, bisphenol F, bisphenol S, andalkyl-substituted biphenol; glycidylamine type epoxy resins obtained byreacting epichlorohydrin and a polyamine such as isocyanuric acid anddiaminodiphenylmethane; and linear aliphatic epoxy resins and alicyclicepoxy resins obtained by oxidizing olefin bonds with peracetic acid.Different kinds of these can also be used together. Of these, one withno coloration is preferable, examples of which include bisphenol A typeepoxy resins, bisphenol F type epoxy resins, bisphenol S type epoxyresins, and triglycidyl isocyanurate.

There are no particular restrictions on the above-mentioned curing agent(B) as long as it will react with an epoxy resin, but one withrelatively little coloration is preferable. Examples include acidanhydride-based curing agents and phenol-based curing agents. Examplesof acid anhydride-based curing agents include phthalic anhydride, maleicanhydride, trimellitic anhydride, pyromellitic anhydride,hexahydrophthalic anhydride, tetrahydrophthalic anhydride, methyl nadicanhydride, nadic anhydride, glutaric anhydride, methylhexahydrophthalicanhydride, and methyltetrahydrophthalic anhydride. Of these acidanhydride-based curing agents, the use of phthalic anhydride,hexahydrophthalic anhydride, tetrahydrophthalic anhydride, ormethylhexahydrophthalic anhydride is preferable. The acidanhydride-based curing agent preferably has a molecular weight of about140 to 200, and an acid anhydride that is from colorless to pale yellowis preferred. These curing agents may be used singly, or two or more maybe used together. It is preferable for the ratio of the epoxy resin andthe curing agent to be such that active groups which can react withepoxy groups (acid anhydride groups or hydroxyl groups) in the curingagent account for 0.5 to 1.5 equivalents, and preferably from 0.7 to 1.2equivalents, per epoxy group equivalent in the epoxy resin. Curing ofthe epoxy resin composition may be slower and the glass transitiontemperature of the cured product thus obtained may be lower if theactive groups is less than 0.5 equivalent, and moisture resistance maydecrease if 1.5 equivalents is exceeded.

There are no particular restrictions on the curing accelerator (C)(curing catalyst), but examples include tertiary amines such as1,8-diaza-bicyclo(5,4,0)undecene-7, triethylenediamine, andtri-2,4,6-dimethylaminomethylphenol; imidazoles such as2-ethyl-4-methylimidazole and 2-methylimidazole; phosphorus compoundssuch as triphenylphosphine, tetraphenylphosphonium tetraphenylborate,and tetra-n-butylphosphonium-o,o-diethylphosphorodithioate; quaternaryammonium salts; organic metal salts; and derivatives of these. These canbe used alone or together. Of these curing accelerators (curingcatalysts), it is preferable to use a tertiary amine, an imidazole, or aphosphorus compound. The amount in which the curing accelerator iscontained is preferably from 0.01 to 8.0 parts by weight (hereinafterreferred to as “weight parts”), and more preferably from 0.1 to 3.0weight parts, per 100 weight parts epoxy resin. A sufficient curingacceleration effect may not be obtained if the curing accelerator(curing catalyst) is contained in an amount of less than 0.01 weightparts, and the cured product may become discolored if the amount is over8.0 weight parts.

The inorganic filler (D) can be at least one type selected from thegroup consisting of silica, alumina, magnesium oxide, antimony oxide,aluminum hydroxide, magnesium hydroxide, barium sulfate, magnesiumcarbonate, and barium carbonate, but a mixture of silica, alumina,antimony oxide, and aluminum hydroxide is preferable from thestandpoints of thermal conductivity, optical reflection characteristics,moldability, and fire retardancy. Also, there are no particularrestrictions on the average particle size of the inorganic filler, but arange of 0.1 to 100 μm is preferable because packing with the whitepigment will be more efficient.

There are no particular restrictions on the white pigment (E), butinorganic hollow particles are preferable, examples of which includesodium silicate glass, aluminum silicate glass, sodium borate glass,alumina, and shirasu (Japanese volcanic ash). The average particle sizeof the white pigment is preferably between 0.1 and 50 μm. If it is lessthan 0.1 μm, the particles will tend to clump and not disperse as well,but if it is over 50 μm, adequate reaction characteristics will tend notto be obtained.

The total packing amount of the white pigment (E) and the inorganicfiller (D) (the filler packing amount) is preferably between 70 and 85vol % with respect tot the total thermosetting light-reflecting resincomposition. The optical reflection characteristics will tend to beinadequate if the filler packing amount is less than 70 vol %, butmoldability will suffer and a substrate will tend to be more difficultto produce if the amount is over 85 vol %.

Examples of the coupling agent (F) include silane coupling agents andtitanate coupling agents. Commonly used silane coupling agents includethose based on epoxysilane, aminosilane, cationic silane, vinylsilane,acrylsilane, mercaptosilane, and compounds of these, which are oftenused in the desired application amount. There are no particularrestrictions on the type of coupling agent or the processing conditions,but the amount of coupling agent contained in the thermosettinglight-reflecting resin composition is preferably no more than 5 wt %.

In addition, an antioxidant, parting agent, ion sequestering agent, orthe like may be added as needed to the thermosetting light-reflectingresin composition.

The thermosetting light-reflecting resin composition containing theabove components is preferably press-moldable at room temperature (0 to35° C.) prior to curing, and preferably has an optical reflectivity ofat least 80% at a wavelength of 350 to 800 nm after curing. Theabove-mentioned press molding can be performed, for example, at roomtemperature, for about 1 to 5 seconds, at a pressure of 0.5 to 2 MPa. Ifthe above-mentioned optical reflectivity is less than 80%, there will bea tendency for the composition not to contribute sufficiently toincreasing the brightness of the optical semiconductor device. Morepreferably, the optical reflectivity is at least 90%.

The spiral flow of the thermosetting light-reflecting resin compositionis preferably at least 50 cm and no more than 300 cm, and morepreferably at least 50 cm and no more than 200 cm, with at least 50 cmand no more than 150 cm being particularly favorable. If the spiral flowis less than 50 cm, the material will not pack as well, so there will bea tendency for unpacked areas to remain in the product. On the otherhand, if the spiral flow is over 300 cm, voids will be more likely to begenerated, and bending strength will tend to decrease. The disk flow ispreferably at least 50 mm, and more preferably at least 80 mm. If thedisk flow is less than 50 mm, there will tend to be unpacked areas orvoids between lead frames. The spiral flow here is the value obtained byinjecting the resin composition (at an injection pressure of 6.9 MPa)into a metal mold (with a mold temperature of 180° C.) having a spiralgroove, and measuring the length of the packed swirl until the resincomposition cures. The disk flow is the value obtained by placing 5 g ofresin composition between two flat plates of a metal mold (with a moldtemperature of 180° C. and a mold weight of 8 kg), and measuring thediameter of the circle over which the resin composition spreads and wetsunder the weight of the mold.

The coefficient of linear expansion of the thermosettinglight-reflecting resin composition is preferably from 10 to 30 ppm/° C.The coefficient of linear expansion here can be found for thethermosetting light-reflecting resin composition either right after itis molded or after it has cured.

There are no particular restrictions on the shape of the resin moldingso long as it has a recessed part that serves as the region for mountingan optical semiconductor element as described above, but it ispreferable that the recessed part side wall (reflector) has a shape toallow light to be reflected upward from the optical semiconductorelement. FIG. 1 illustrates an embodiment of an optical semiconductorelement mounting package 110 of the present invention, comprising aresin molding 103, lead electrodes 105, a recessed part 200 that servesas the region for mounting an optical semiconductor element, and a Ni/Agplating film 104.

<Method for Manufacturing a Package>

There are no particular restrictions on the method for manufacturing theoptical semiconductor element mounting package of the present invention,but preferably the thermosetting light-reflecting resin composition andthe lead electrodes are formed integrally by transfer molding. Formingthem by transfer molding makes it less likely that there will be a gapbetween the lead electrodes and the resin molding. More specifically,for example, the lead electrodes are placed in a metal mold of aspecific shape, a thermosetting light-reflecting resin composition isinjected through a resin injection opening in the mold, and thecomposition is preferably cured at a mold temperature of 170 to 190° C.,a molding pressure of 2 to 8 MPa, and for 60 to 120 seconds. The moldingis taken out of the mold, and then heat cured for 1 to 3 hours at anafter-curing temperature of 120 to 180° C.

<Optical Semiconductor Device>

The optical semiconductor device of the present invention comprises atleast the optical semiconductor element mounting package of the presentinvention, an optical semiconductor element mounted on the bottom faceof a recessed part of this optical semiconductor element mountingpackage, and a transparent sealing resin layer formed in the recessedpart so as to cover an optical semiconductor element.

The above-mentioned optical semiconductor element (light emittingelement) is disposed, for example, on a negative lead electrode or apositive lead electrode exposed on the bottom face of the recessed partof the package, the n electrode and the negative lead electrode areconnected by wire bonding, and similarly the p electrode and thepositive lead electrode are connected by wire bonding. Also, in anelement configuration in which the n electrode is formed at the top partof the light emitting element and the p electrode is formed at thebottom part of the light emitting element, the p electrode is bonded bysilver paste or another such die bonding material on the positive leadelectrode, while the n electrode and the negative lead electrode areconnected by wire bonding. Disposing the light emitting element on thelead electrodes in this manner is favorable because heat dissipationfrom the light emitting element is improved. The light emitting elementhere is a gallium nitride compound semiconductor element capable ofemitting blue light, for example, and said element is configured, forexample, such that nitride semiconductor layers including an n-typelayer, an active layer, and a p-type layer is formed on a sapphiresubstrate, parts of the active layer and the p-type layer are removedand an n electrode is formed over the exposed n-type layer, and a pelectrode is formed over the p-type layer.

The above-mentioned transparent sealing resin layer protects the lightemitting element from external force, moisture, and so forth. With astructure in which the lead electrodes and the electrodes of the lightemitting element are connected with wires, this layer also functions toprotect these wires. The transparent sealing resin layer also needs tobe highly transmissive to light so that the light from the lightemitting element can be efficiently transmitted to the outside. As tothe specific material of the transparent sealing resin used in thetransparent sealing resin layer, epoxy resins, silicone resins, acrylicresins, and the like are suitable, and a coloring dye or pigment canalso be added in order to subject the light from the light emittingelement to a specific filtering effect.

FIG. 2 illustrates an embodiment of the optical semiconductor device ofthe present invention, in which an optical semiconductor element 100 ismounted at a specific location on the bottom of an optical semiconductorelement mounting region (recessed part) 200 of the optical semiconductorelement mounting package 110 of the present invention, the opticalsemiconductor element 100 and lead electrodes 105 are electricallyconnected by a known method such as with a bonding wire 102 or solderbump 107, and the optical semiconductor element 100 is covered by atransparent sealing resin 101 that includes a known fluorescent material106.

EXAMPLES

The present invention will now be described by giving examples, but thepresent invention is not limited to or by these examples.

Example 1

(Lead Frame)

A copper frame with a thickness of 0.15 mm was subjected to a standardphotoetching process to form a circuit including lead electrodes, afterwhich this circuit was subjected to silver electroplating to produce alead frame.

TABLE 1 <Thermosetting Light-Reflecting Resin Composition> epoxy resin:triglycidyl isocyanurate (100 epoxy 100 weight parts equivalents) curingagent: hexahydrophthalic anhydride 140 weight parts curing accelerator:tetra-n-butylphosphonium-o,o- 2.4 weight parts diethylphosphorodithioateinorganic filler: molten silica (20 μm average 600 weight parts particlesize) alumina (1 μm average particle size) 890 weight parts whitepigment: sodium borate glass balloons (27 μm 185 weight parts averageparticle size) coupling agent: γ-glycidoxypropyltrimethoxysilane 19weight parts antioxidant: 9,10-dihydro-9-oxa-10- 1 weight partphosphaphenanthrene-10-oxide

A material with the above composition was kneaded with a roll for 10minutes at a kneading temperature of 30 to 40° C. to produce athermosetting light-reflecting resin composition. The spiral flow of theresulting resin composition was 140 cm (curing time of 90 seconds), andthe disk flow was 85 mm (curing time of 90 seconds). The opticalreflectivity of the resulting resin composition was over 90%. Thisoptical reflectivity value was obtained as follows. The above-mentionedresin composition was transfer molded at a molding temperature of 180°C., a molding pressure of 6.9 MPa, and a curing time of 90 seconds,after which it was post-cured for 2 hours at 150° C. to produce a testpiece with a thickness of 2.0 mm. The reflectivity of this test piecewas measures at a wavelength of 350 to 850 nm using a model V-750integrating sphere type of spectrophotometer (made by JASCOCorporation).

(Formation of Optical Semiconductor Element Mounting Package)

The lead frame obtained above was positioned in and attached to a metalmold, the thermosetting light-reflecting resin composition obtainedabove was injected into the mold, and transfer molding was performed ata mold temperature of 180° C., for 90 seconds, at 6.9 MPa, whichproduced a optical semiconductor element mounting package that had arecessed part in the element mounting region and in which the positiveand negative lead electrodes were exposed at the bottom face of thisrecessed part.

(Manufacture of Optical Semiconductor Device)

An LED element was fixed with a die bonding material to the leadelectrodes on the bottom face of the recessed part of the opticalsemiconductor element mounting package obtained above, and the LEDelement was affixed over a terminal by heating for 1 hour at 150° C.After this, the LED element and the terminal were electrically connectedwith a gold wire.

Net, a transparent sealing resin with the following composition wasapplied by potting to the above-mentioned recessed part so as to coverthe LED element, then heated and cured for 2 hours at 150° C. to producean optical semiconductor device (SMD-type LED).

TABLE 2 <Composition of Transparent Sealing Resin> hydrogenatedbisphenol A type epoxy resin (trade 90 weight parts name Denacol EX252,made by Nagase ChemteX) alicyclic epoxy resin (trade name CEL-2021P,made 10 weight parts by Daicel) 4-methylhexahydrophthalic anhydride(trade name 90 weight parts HN-5500E, made by Hitachi Chemical)2,6-di-tert-butyl-4-methylphenol BHT 0.4 weight part2-ethyl-4-methylimidazole 0.9 weight part

Example 2

TABLE 3 <Thermosetting Light-Reflecting Resin Composition> epoxy resin:triglycidyl isocyanurate (100 epoxy 100 weight parts equivalents) curingagent: hexahydrophthalic anhydride 125 weight parts curing accelerator:tetra-n-butylphosphonium-o,o- 2.4 weight partsdiethylphlosphorodithioate inorganic filler: molten silica (20 μmaverage 720 weight parts particle size) alumina (1 μm average particlesize) 640 weight parts white pigment: silica balloons (3 μm average 435weight parts particle size) coupling agent:γ-glycidoxypropyltrimethoxysilane 9 weight parts antioxidant:9,10-dihydro-9-oxa-10- 1 weight part phosphaphenanthrene-10-oxide

A material with the above composition was kneaded with a roll for 10minutes at a kneading temperature of 30 to 40° C. to produce athermosetting light-reflecting resin composition. The spiral flow of theresulting resin composition was 100 cm (curing time of 90 seconds), andthe disk flow was 55 mm (curing time of 90 seconds). The opticalreflectivity of the resulting resin composition after curing was over90% (350 to 850 nm).

The thermosetting light-reflecting resin composition obtained above wasused to produce an optical semiconductor element mounting package and anoptical semiconductor device in the same manner as in Example 1.

The optical semiconductor devices of the examples manufactured as abovehad good bonding strength at the interface between the leads and thepackage, and no gaps were noted at this interface. Each device wasallowed to stand for 24 hours at 85° C. and 85% relative humidity (RH),after which the interface between the resin molding and the transparentsealing resin layer or the lead electrodes was checked for separation,but no separation was noted, and it was confirmed that almost nomoisture had infiltrated. Therefore, the optical semiconductor devicesof the examples can be considered to have excellent reliability, such asreflow resistance and migration resistance.

What is claimed is:
 1. An optical semiconductor element mounting packagehaving a recessed part that serves as an optical semiconductor elementmounting region, wherein the package is formed by integrating: a resinmolding composed of a thermosetting light-reflecting resin composition,which forms at least the side faces of the recessed part; and at least apair of positive and negative lead electrodes, each of the positive andnegative lead electrodes having opposed first and second major surfacesextending continuously from an inner end to an opposite end, the pair ofpositive and negative lead electrodes being disposed with their innerends opposite each other so that inner portions of the first majorsurface of the positive and negative lead electrodes form part of thebottom face of the recessed part, wherein there is no gap at a jointface between the resin molding and the lead electrodes, the inner endsof the positive and negative lead electrodes are separated by the resinmolding composed of the thermosetting light-reflecting resin compositionand at least portions of the second major surface of the positive andnegative lead electrodes are not in contact with the resin moldingcomposed of the thermosetting light-reflecting resin composition,wherein the thermosetting light-reflecting resin composition includestriglycidyl isocyanurate as (A) an epoxy resin.
 2. The opticalsemiconductor element mounting package according to claim 1, wherein theintegration of the resin molding and the positive and negative leadelectrodes is performed by transfer molding.
 3. The opticalsemiconductor element mounting package according to claim 2, wherein thethermosetting light-reflecting resin composition includes a filler. 4.The optical semiconductor element mounting package according to claim 2,wherein the thermosetting light-reflecting resin composition includescomponents: (A) an epoxy resin; (B) a curing agent; (C) a curingaccelerator; (D) an inorganic filler; (E) a white pigment; and (F) acoupling agent, and is a resin composition whose optical reflectivity ata wavelength of 350 to 800 nm is at least 80% and which can be pressmolded at normal temperature (0 to 35° C.).
 5. The optical semiconductorelement mounting package according to claim 4, wherein the inorganicfiller (D) is at least one type selected from the group consisting ofsilica, alumina, magnesium oxide, antimony oxide, aluminum hydroxide,magnesium hydroxide, barium sulfate, magnesium carbonate, and bariumcarbonate.
 6. The optical semiconductor element mounting packageaccording to claim 4, wherein the average particle size of the whitepigment (E) is between 0.1 and 50 μm.
 7. The optical semiconductorelement mounting package according to claim 4, wherein the total amountof the inorganic filler (D) and the white pigment (E) is from 70 to 85vol % with respect to the entire thermosetting light-reflecting resincomposition.
 8. The optical semiconductor device comprising: the opticalsemiconductor element mounting package according to claim 2; an opticalsemiconductor element mounted on the bottom face of a recessed part ofthe package; and a transparent sealing resin layer that covers theoptical semiconductor element in the recessed part.
 9. The opticalsemiconductor element mounting package according to claim 2, wherein thesecond major surface of each of the positive and negative leadelectrodes not in contact with the resin molding composed of thethermosetting light-reflecting resin composition is exposed at a rearface of the optical semiconductor element mounting package.
 10. Theoptical semiconductor element mounting package according to claim 9,wherein the positive and negative lead electrodes are not bent.
 11. Theoptical semiconductor element mounting package according to claim 1,wherein the thermosetting light-reflecting resin composition includes afiller.
 12. The optical semiconductor element mounting package accordingto claim 1, wherein the thermosetting light-reflecting resin compositionincludes components: (A) an epoxy resin; (B) a curing agent; (C) acuring accelerator; (D) an inorganic filler; (E) a white pigment; and(F) a coupling agent, and is a resin composition whose opticalreflectivity at a wavelength of 350 to 800 nm is at least 80% and whichcan be press molded at normal temperature (0 to 35° C.).
 13. The opticalsemiconductor element mounting package according to claim 12, whereinthe inorganic filler (D) is at least one type selected from the groupconsisting of silica, alumina, magnesium oxide, antimony oxide, aluminumhydroxide, magnesium hydroxide, barium sulfate, magnesium carbonate, andbarium carbonate.
 14. The optical semiconductor element mounting packageaccording to claim 12, wherein the average particle size of the whitepigment (E) is between 0.1 and 50 μm.
 15. The optical semiconductorelement mounting package according to claim 12, wherein the total amountof the inorganic filler (D) and the white pigment (E) is from 70 to 85vol % with respect to the entire thermosetting light-reflecting resincomposition.
 16. The optical semiconductor device comprising: theoptical semiconductor element mounting package according to claim 1; anoptical semiconductor element mounted on the bottom face of a recessedpart of the package; and a transparent sealing resin layer that coversthe optical semiconductor element in the recessed part.
 17. The opticalsemiconductor element mounting package according to claim 1, wherein thesecond major surface of each of the positive and negative leadelectrodes not in contact with the resin molding composed of thethermosetting light-reflecting resin composition is exposed at a rearface of the optical semiconductor element mounting package.
 18. Theoptical semiconductor element mounting package according to claim 17,wherein the positive and negative lead electrodes are not bent.